New Harbor and Windless Bight Seismic Data for ANDRILL

This was a joint project between scientists and scientific programmes of the
US, UK, Germany, and New Zealand to collect geophysical and site survey data in
support of the ANDRILL Program. Surveys were conducted over two successive
Antarctic field seasons.

In the first season, the program acquired 40 km of seismic reflection data in
the New Harbour area and on the Ross/McMurdo ice shelf between Hut Point
Peninsula and Ross Island. Three 80 km line grids (New Harbour, Windless
Bight/McMurdo Ice Shelf, Southern McMurdo Ice Shelf) were traversed with a
magnetometer and gradiometer for gravity and magnetic measurements. An area of
5000 km2 was covered by a helicopter-borne aeromagnetic survey between Hut
Point Peninsula, White Island and Minna Bluff/Brown Peninsula. Immediate
scientific goals were to identify sedimentary basins beneath New Harbour and
the McMurdo and Southern McMurdo Ice Shelves, determine sediment thickness and
the nature of bounding faults. Beneath New Harbour, a series of 200-500 m
deep/thick channels and channel fill sediments are identified that relate to
the Taylor and Ferrar paleovalleys. The Taylor sequence appears to pre-date and
be overprinted by the Ferrar sequence. The channel sediments overlie an older
east/north east dipping set of strata cored by CIROS-1. The stratal sets are
bounded west and east by major north-south trending faults related to the
Transantarctic Mountain front, however, making it difficult to correlate
directly to the nearby CIROS and MSSTS drillholes.

In the second season, 40 km of seismic reflection and gravity data was
collected from the McMurdo and southern McMurdo Ice Shelves. Immediate
scientific goals were to gain new knowledge of the role of volcanism on the
development of the Victoria Land Basin, and to better understand the
relationship between volcanism and sedimentation in the vicinity of Ross Island
and Minna Bluff. In terms of ANDRILL drill site location this new data has
elucidated 2 thick sedimentary records under the McMurdo Ice Shelf: (1) A >1000
m thick sedimentary fill beneath the 900 m deep flexural moat around Ross
Island between Ross and White Islands. (2) A >600 m sedimentary record under
500 m of water in the flexural moat related to Mt Discovery/Morning between Mt
Discovery and Black Island. A total of four seismic lines have now been
acquired in Windless Bight which elucidate sedimentray basins that have formed
as a consequence of loading of the crust/seafloor by Mt Terror volcano and the
Younger Erebus volcano. This new data allows us to understand the geometry and
age of the drilling targets. The data will also be used in developing models of
crustal flexure as a result of volcanic loading.

Key results include:
1. Identification of a c. 500 m composite cross-cutting Miocene-Pliocene
channel sequence beneath New Harbour.

2. Identification of up to 1 km of sediment under the McMurdo Ice Shelf, in
the "moat" east of Ross Island that has accumulated in the last 5 million
years.

3. New estimates on the water depth beneath the McMurdo Ice Shelf between
Mt Discovery and Black Island (up to 600 m)

4. Identification of up to 600 m of sediment under the McMurdo Ice Shelf,
in the moat between Mt Discovery and Black Island.

5. The geometry from seismic stratigraphy of the flexure "moat-fill" basins
in Southern McMurdo Sound.

6. An estimate of sediment age based on the age of volcanic loading of the
crust and development of sedimentary basins.

7. The relationship of the volcanoes to the adjacent sediments.

8. Greatly improved understanding of the water depth, stratigraphy and
rates of ice movement likely to be encountered at proposed ANDRILL drill sites.

Funding Agencies:

University of Otago, NZ - FRST-funded "Palaeomagentic records of climate and
environmental change" and ORG-funded "Physiography, recent history and
vulnerability of the McMurdo Ice Shelf, Antarctica".

University of Oxford, UK - NERC-funded "Evolution of Sedimentary Basins in
Southern McMurdo Sound: Implications for Antarctic tectonic and climate
history".

University of Nebraska, USA - NSF-funded "Seismic and stratigraphic data
acquisition and integration for Cenozoic tectonic and paleoenvironmental
analysis in McMurdo Sound"

Geological and Nuclear Sciences, NZ - FRST-funded "Antarctic Drivers of
Climate Change Objective"

Victoria University of Wellington, Antarctic Research Centre - "FRST-funding
Antarctic Climate Evolution programme"

BGR, Germany - "Aeromagentic investigations of the McMurdo volcanoes and
their expression beneath the Ross Ice Shelf in support of ANDRILL".

Personnel supported by project:

Dr. T. Naish, Institute of Geological and Nuclear Sciences, Wellington, New
Zealand
Dr. G. Wilson, University of Oxford, Oxford, UK and University of Otago,
Dunedin, New Zealand
Mr. Alex Pyne, Victoria University, Wellington, New Zealand
Dr. Mohammed Ali (postdoctoral researcher), University of Oxford, UK
Mr. Alan Aitken (graduate student), University of Otago, Dunedin, New Zealand
Mr. Cliff Atkins (graduate student), Victoria University, Wellington, New
Zealand
Ms. Natalie Balfour (graduate student), Victoria University, Wellington, New
Zealand
Mr. Hayden Caskey, Webster Drilling Ltd, Wellington, New Zealand
Mr. Andrew Clifford (graduate student), University of Otago, Dunedin, New
Zealand
Mr. Mike Collins, Independent, Christchurch, New Zealand
Dr. Detlef Damaske, BGR, Germany
Mr. Mike Finnemore (graduate student), University of Canterbury,
Christchurch, New Zealand
Mr. Ricky Henderson (undergraduate student), Victoria University, Wellington,
New Zealand
Mr. Mathew Hill, Institute of Geological and Nuclear Sciences, Wellington,
New Zealand
Mr. Huw Horgan (graduate student), Victoria University, Wellington, New
Zealand
Mr. Tom Jordan (graduate student), University of Oxford, UK
Mr. Tony Kingan, Webster Drilling Ltd, Wellington, New Zealand
Dr. Mark Lavell, British Antarctic Survey, UK
Mr. Jono Leitch, Industrial research Limited, Wellington, New Zealand
Dr. Dieter Moeller, BGR, Germany
Ms. Sarah Thornton, Institute of Geological and Nuclear Sciences, Wellington,
New Zealand
Ms. Kirsty Tinto (graduate student), University of Oxford, UK
Mr. Joel Vanderburg, Independent, Dunedin, New Zealand
Mr. Hayden Webster, Webster Drilling Ltd, Wellington, New Zealand
Dr. Jason Whitehead (postdoctoral researcher), University of Nebraska, USA
Dr. Julio Friedmann, University of Maryland, USA